Cleaning apparatus and cleaning method, coater/developer and coating and developing method, and computer readable storing medium

ABSTRACT

A cleaning apparatus includes a first substrate-holding portion configured to hold a first area of a back surface of the substrate so that the top surface is kept face up; a second substrate-holding portion configured to hold a second area of the back surface of the substrate, the second area being not overlapped with the first area, and rotate the substrate; a top-surface cleaning nozzle configured to supply a top surface cleaning fluid to a top surface of the substrate; a bevel cleaning nozzle configured to supply a bevel cleaning fluid to a bevel portion of the substrate; a cleaning fluid supplying portion configured to supply a back surface cleaning fluid to the back surface of the substrate held by the first or the second substrate-holding portion; and a cleaning member configured to clean the back surface of the substrate held by the first or the second-substrate holding portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate cleaning technology forcleaning substrates such as a semiconductor wafer and a glass substrate(Liquid Crystal Display (LCD) substrate) prior to immersion exposure.

2. Description of the Related Art

In a fabrication process of a semiconductor device or an LCD,photolithography is indispensable in order to form a predeterminedphotoresist pattern on a substrate. The photolithography includes aseries of processes of coating photoresist solution in order to form aresist film on the substrate such as a semiconductor wafer (referred toas a wafer below), exposing the resist film with exposure light througha photomask, and developing the resist film. Such processes aregenerally carried out in a resist pattern forming system having acoater/developer for forming the resist film and developing the resistfilm after the exposure and an exposure apparatus connected to thecoater/developer.

With further reduction in a circuit pattern and a film thickness,increased resolution of the lithography is greatly demanded. In order toaddress such demand, so-called immersion exposure is underconsideration. In immersion exposure process, a liquid layer is formedon the photoresist film and the exposure is carried out through theliquid layer on the photoresist film. Specifically, the liquid layer isformed between the wafer and a projection lens provided in an exposureapparatus, and the exposure light is illuminated onto the photoresistfilm through the projection lens and the liquid layer, therebytransferring a predetermined circuit pattern in the photomask onto thephotoresist film. More specifically, the projection lens is positionedin a predetermined chip area in order to expose the chip area, and thenlaterally slid while the liquid layer is kept between the wafer and theprojection lens, so that the projection lens is positioned in theadjacent chip area, thereby exposing the adjacent chip area. Such aprocedure is repeated to expose all the chip areas in the wafer.

SUMMARY OF THE INVENTION

In such immersion exposure process, because the exposure is carried outby sliding the projection lens and thus the exposure apparatus with theliquid layer kept between the projection lens and the wafer, if there isa particle on the wafer, the particle may be included in the liquidlayer. If this happens, the particle can also slide with the projectionlens and the liquid layer, so that the particle may be transcribed tothe photoresist film in all the chip areas. In other words, even ifthere is a particle on only a part of the wafer, the entire wafer may beaffected by the particle. In order to address such a problem, the waferhas to be cleaned before the immersion exposure (see Patent Document 1,for example.)

In addition, because a peripheral portion of the wafer, which includes abevel portion 10 (slanted portion) shown in FIG. 1, is outside of a chipforming area, the photoresist film and an anti-reflection film formed onthe peripheral portion are unnecessary and removed with solvent in orderto avoid particles generating from the peripheral portion, so that stepsmay be made in the portion, as shown in FIG. 1 that illustrates a waferW, an anti-reflection film 11, a photoresist film 12, and a top coat 13.In such a structure, the top coat 13 may be easily peeled off from thebevel portion 10. Moreover, because the bevel portion 10 is met by awafer transferring mechanism when the wafer W is transferred, the topcoat 13 may be peeled off by the wafer transferring mechanism, which maycause particles to spread over a top surface of the wafer W. A cleaningmethod of cleaning the bevel portion 10 has been proposed in order toremove the particles in the bevel portion 10 prior to the immersionexposure. (See Patent Document 2, for example.)

Furthermore, particles on a back surface of the wafer have been paidattention to in recent years. When particles are on the back surface ofthe wafer, the particles are sandwiched between the wafer and a waferstage on which the wafer is placed in the exposure apparatus, therebycausing warpage of the wafer. Such warpage may cause defocusing when thewafer is exposed to the exposure light, which can be a problem as thecircuit dimensions are further reduced. Therefore, the back surface ofthe wafer also has to be cleaned prior to the immersion exposure.

Cleaning the wafer including the bevel portion and the back surfacegenerally needs to be carried out in a cleaning apparatus providedoutside of the photoresist pattern forming system before the wafer W istransferred into the exposure apparatus, because a highly cleanenvironment is kept in the photoresist pattern forming system. However,transferring the wafer from the photoresist pattern forming system tothe cleaning apparatus and otherwise may be disadvantageous fromviewpoint of particles. In addition, it has been found that evenparticles of only 5 to 10 μm may cause warpage of the wafer W, resultingin the defocus problem in aforementioned the immersion exposure.Therefore, pre-cleaning the wafer W is preferably carried out in acleaning unit coupled to the photoresist pattern forming system in ahighly clean environment and before the immersion exposure process.

The wafer is cleaned generally in the following manner. First, the waferis firmly fixed by, for example, a vacuum chuck or a mechanical chuck.Second, deionized water (referred to as DIW below) is supplied onto thewafer. Then, a brush is pressed onto the wafer with the DIW continuouslysupplied onto the wafer, and the brush and the wafer are relativelyslid, thereby removing the particles. Because the wafer is transferredin a face-up manner in the photoresist pattern forming system, the waferhas to be reversed when cleaning the back surface of the wafer.Therefore, when the cleaning unit that is capable of cleaning the backsurface of the wafer is incorporated in the photoresist pattern formingsystem, a so-called reverser for inverting the wafer has to be providedbetween the cleaning unit and the wafer transferring mechanism. However,such a reverser requires additional space for the reverser itself andfor reversing the wafer. As a result, the photoresist pattern formingsystem tends to be larger. On the other hand, the brush may be providedbelow the wafer so that the back surface of the wafer is cleaned frombelow in order to eliminate the need of the reverser. However, becausethe back surface of the wafer is covered at least in part by the wafertransferring mechanism, the entire back surface of the wafer cannot becleaned in such a configuration.

In addition, even though the photoresist pattern forming system alreadyincludes plural units including coating units, developing units,pre-treatment/post-treatment units, and the like, there is a demand forincreasing the number of units in order to increase throughput, whilerealizing a reduced foot print of the system. It is contrary to such ademand to separately incorporate a top surface cleaning unit, a backsurface cleaning unit, and a bevel cleaning unit. Moreover, it takesmore time to separately clean the top surface, the back surface, and thebevel portion of the wafer and to transfer the wafer to each cleaningunit, which is disadvantageous from a viewpoint of throughput.

Furthermore, a hydrophobizing process for improving adhesiveness of ananti-reflection film solution and the photoresist solution is carriedout in order to avoid peeling of the anti-reflection film and thephotoresist film during the immersion exposure. Because thehydrophobizing process is carried out using vapor of a hydrophobizingagent, the vapor flows around the wafer edge to reach a part of the backsurface of the wafer. Specifically, a back surface area of about 15 mmwidth from the wafer edge is hydrophobized, as shown in the bottom leftof FIG. 2, in which a hatched line portion 14 represents thehydrophobized area.

In other words, there are the hydrophobized area and an unhydrophobizedarea on the back surface of the wafer. While the brush cleaning iseffective for the unhydrophobized area, the brush is worn away on thehydrophobized area because the area is not easily wet with DIW, whichmay generate many particles contaminating the wafer.

Therefore, at least the following should be considered. First, the topsurface, the bevel portion, and the back surface of the wafer should becleaned before the exposure process, for example, in the case ofimmersion exposure. In addition, such cleaning needs to be carried outin one module. Moreover, appropriate cleaning techniques should bechosen for a hydrophobic area and an unhydrophobic area of the wafer.

For example, the patent document 1 below describes a cleaning techniquefor cleaning the top surface of the wafer before immersion exposure, andthe patent document 2 describes a technique for removing the photoresistfilm in the bevel portion of the wafer. However, these documents 1, 2 donot disclose a cleaning technique for cleaning the back surface of thewafer, or a cleaning technique for cleaning the top surface, the bevelportion, and the back surface of the wafer W while maintaining both asmaller footprint of the cleaning apparatus and a higher productionthroughput.

Patent document 1: Japanese Patent Application Laid-Open Publication No.2006-80403.

Patent document 2: Japanese Patent Application Laid-Open Publication No.2007-214279.

The present invention has been made in view of the above, and isdirected to a substrate cleaning technology for cleaning a top surface,a bevel portion, and a back surface of a substrate such as asemiconductor wafer and a glass substrate for an LCD prior to immersionexposure in a single cleaning apparatus.

A first aspect of the present invention provides a cleaning apparatusthat cleans a substrate on which a photoresist film is formed, thephotoresist film being to be exposed to exposure light with a liquidlayer being formed on a top surface of the photoresist film. Thecleaning apparatus includes a first substrate holding portion configuredto hold the substrate at a first area in a back surface of the substrateso that the top surface is kept face up; a second substrate holdingportion configured to hold the substrate at a second area in the backsurface of the substrate, the second area being not overlapped with thefirst area, and rotate the substrate around a substantial center of thesubstrate; a top surface cleaning nozzle configured to supply a topsurface cleaning fluid to a top surface of the substrate that may berotated by the second substrate holding portion; a bevel cleaning nozzleconfigured to supply a bevel cleaning fluid to a bevel portion of thesubstrate that may be rotated by the second substrate holding portion; acleaning fluid supplying portion configured to supply a back surfacecleaning fluid to a back surface of the substrate held by the firstsubstrate holding portion or the second substrate holding portion; and acleaning member configured to clean the back surface of the substrateheld by the first substrate holding portion or the second substrateholding portion.

A second aspect of the present invention provides a cleaning apparatusaccording to the first aspect, further including a moving mechanismconfigured to laterally move the first substrate holding portion inrelation to the second substrate holding portion; and an elevationmechanism configured to vertically move the first substrate holdingportion in relation to the second substrate holding portion.

A third aspect of the present invention provides a cleaning apparatusaccording to the first or the second aspect, further including acontroller configured to output an instruction in accordance with whichone part of the back surface of the substrate, the one part includingthe second area, is cleaned by the cleaning member while the substrateis held by the first substrate holding portion, the substrate istransferred from the first substrate holding portion to the secondsubstrate holding portion, and another part of the back surface of thesubstrate, the another part not including the second area, is cleaned bythe cleaning member while the substrate is rotated by the secondsubstrate holding portion.

A fourth aspect of the present invention provides a cleaning apparatusaccording to the third aspect, wherein the controller is furtherconfigured to output another instruction in accordance with which, in atime period during which the one part of the back surface, the one partnot including the second area, is cleaned by the cleaning member, thetop surface cleaning fluid is supplied to the top surface of thesubstrate from the top surface cleaning nozzle, and the bevel cleaningfluid is supplied to the bevel portion of the substrate from the bevelcleaning nozzle.

A fifth aspect of the present invention provides a cleaning apparatusaccording to any one of the first through the fourth aspects, furtherincluding a back periphery cleaning nozzle configured to supply a backperiphery cleaning fluid to a back peripheral area in the substrate heldand rotated around the substantial center of the substrate by the secondsubstrate holding portion.

A sixth aspect of the present invention provides a cleaning apparatusaccording to the fifth aspect, wherein the controller is configured tooutput yet another instruction in accordance with which, in a timeperiod during which one part of the back surface, the one part notincluding the second area, is cleaned by the cleaning member, the topsurface cleaning fluid is supplied to the top surface of the substratefrom the top surface cleaning nozzle, the bevel cleaning fluid issupplied to the bevel portion of the substrate from the bevel cleaningnozzle, and the back periphery cleaning fluid is supplied to the backsurface of the substrate from the back periphery cleaning nozzle.

A seventh aspect of the present invention provides a coater anddeveloper including a coating unit configured to coat a photoresist filmon a top surface of a substrate; a developing unit configured to supplya developing solution to the photoresist film coated on the top surfaceof the substrate, the photoresist film being exposed to exposure lightwith a liquid layer being formed on the photoresist film, therebydeveloping the photoresist film; and a cleaning apparatus according toany one of the first through the sixth aspects.

An eighth aspect of the present invention provides a cleaning methodthat cleans a substrate on which a photoresist film is formed, thephotoresist film being to be exposed to exposure light with a liquidlayer being formed on a top surface of the photoresist film. Thecleaning method includes a second area cleaning step, wherein a firstarea in a back surface of the substrate is held with a first substrateholding portion, the back surface being kept face down, and a secondarea in the back surface of the substrate, the second area being notoverlapped with the first area, is cleaned prior to immersionlithography; a substrate holding step, wherein the substrate istransferred from the first substrate holding portion to a secondsubstrate holding portion, and the second area in the back surface ofthe substrate is held by the second substrate holding portion; a topsurface cleaning step, wherein a top surface cleaning fluid is suppliedto a top surface of the substrate that is held and rotated around avertical axis by the second substrate holding portion, thereby cleaningthe top surface; a bevel cleaning step, wherein a bevel cleaning fluidis supplied to a bevel portion of the substrate that is held and rotatedaround a vertical axis by the second substrate holding portion, therebycleaning the bevel portion; and a back surface cleaning step, whereinone part of the back surface of the substrate, the one part notincluding the second area, is cleaned, the substrate being held androtated around the substantial center of the substrate by the secondsubstrate holding portion, thereby cleaning the one part.

A ninth aspect of the present invention provides a cleaning methodaccording to the eighth aspect, wherein the top surface cleaning step,the bevel cleaning step, and the back surface cleaning step areoverlapped time-wise.

A tenth aspect of the present invention provides a cleaning methodaccording to the eighth or the ninth aspect, further including a backperiphery cleaning step, wherein a periphery cleaning fluid is suppliedto a periphery area in the back surface of the substrate that is heldand rotated around the substantial center of the substrate by the secondsubstrate holding portion, thereby cleaning the periphery area.

An eleventh aspect of the present invention provides a cleaning methodaccording to the tenth aspect, wherein the top surface cleaning step,the bevel cleaning step, the back surface cleaning step, and the backperiphery cleaning step are overlapped time wise.

A twelfth aspect of the present invention provides a coating anddeveloping method including steps of forming a photoresist film on asubstrate; cleaning the substrate on which the photoresist film isformed in accordance with the cleaning method according to any one ofthe eighth through the eleventh aspects; and exposing the photoresistfilm to exposure light through a liquid layer formed on the photoresistfilm.

A thirteenth aspect of the present invention provides a computerreadable storage medium storing a computer program to be used in acleaning apparatus that cleans a substrate on which a photoresist filmis formed, the photoresist film being to be exposed to exposure lightwith a liquid layer being formed on a top surface of the photoresistfilm, the computer program, when executed by a computer, comprisingsteps that cause the cleaning apparatus to carry out a cleaning methodaccording to the eighth through the eleventh aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a bevel portion of a wafer on whichan anti-reflection film, a photoresist film, and a top coat are formed;

FIG. 2 is a cross-sectional view of a wafer, illustrating that aperipheral area in the back surface of the wafer may become hydrophobic;

FIG. 3 is a plan view of an example of photoresist pattern formingsystem including a photoresist coater/developer into which a cleaningapparatus according to a first embodiment of the present invention isincorporated;

FIG. 4 is a perspective view of the photoresist coater/developer shownin FIG. 3;

FIG. 5 is a perspective view of the cleaning apparatus according to thefirst embodiment of the present invention;

FIG. 6 is a plan view of the cleaning apparatus shown in FIG. 5;

FIG. 7 is a cross-sectional view of the cleaning apparatus shown in FIG.5;

FIG. 8 is a perspective view of an air-knife provided in the cleaningapparatus shown in FIG. 5;

FIG. 9 illustrates a positional relationship between a bevel portion ofa wafer and bevel cleaning nozzles;

FIG. 10 is an explanatory plan view of a first cleaning area and asecond cleaning area of a wafer;

FIG. 11 is a flowchart showing a cleaning process carried out in acleaning apparatus according to an embodiment of the present invention;

FIGS. 12A through 12C are step-by-step explanatory cross-sectional viewsof the cleaning apparatus according to the embodiment of the presentinvention;

FIGS. 13A and 13B are step-by-step explanatory cross-sectional views ofthe cleaning apparatus according to the embodiment of the presentinvention;

FIGS. 14A and 14B illustrate a positional relationship between a wafer,a spin chuck, suction pads, and a brush in the cleaning apparatusaccording to the embodiment of the present invention;

FIGS. 15A and 15B are explanatory views of a wafer being cleaned in thecleaning apparatus according to the embodiment of the present invention;

FIG. 16 is a plan view of a cleaning apparatus according to a secondembodiment of the present invention;

FIGS. 17A and 17B are explanatory cross-sectional views of the cleaningapparatus according to the second embodiment of the present invention;and

FIG. 18 is an explanatory cross-sectional view of the cleaning apparatusaccording to the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In a cleaning apparatus according to embodiments of the presentinvention, because the substrate is held from a back surface of thesubstrate so as to be face up when the back surface of the substrate iscleaned, there is no need for a reverser that reverses the substrate forthe purpose of cleaning the back surface of the substrate. Therefore,the space required to implement the reverser and the space required toreverse the substrate are not required, thereby making the cleaningapparatus compact.

In addition, because the substrate is once held by a first substrateholding portion and then held by a second substrate holding portion, theback surface of the substrate may be cleaned.

Moreover, because the substrate is held face up when the back surface ofthe substrate is cleaned, the top surface, the bevel portion, and theback surface of the substrate are cleaned in one cleaning apparatus.Therefore, a substrate transferring time can be reduced, therebyincreasing the production throughput, when compared to use ofcorresponding cleaning apparatuses for cleaning the top surface, thebevel portion, and the back surface of the substrate.

Furthermore, the cleaning apparatus need only occupy a space sufficientfor one cleaning apparatus in a coater/developer when incorporated inthe coater/developer. Therefore, a footprint of the coater/developer isnot increased and substrate cleaning can be carried out within thecoater/developer before immersion exposure.

<First Embodiment>

Referring to FIGS. 3 and 4, a photoresist pattern forming system isdescribed that integrates a coater/developer according to a firstembodiment of the present invention. This system includes thecoater/developer and an immersion exposure apparatus coupled to thecoater/developer. In FIG. 3, a carrier station B1 has carrier stages 120where carriers C1 are placed. The carriers C1 can house, for example,thirteen semiconductor wafers (referred to as a wafer below) assubstrates in an airtight manner. In addition, the carrier station B1has opening/closing portions 121 provided on the outlet side of thecarriers C1 placed on the carrier stages 120, and a transfer mechanismA1 that transfers the wafers from/into the carrier C1 through theopening/closing portions 121.

When seen in an X direction in FIG. 3 from the carrier station B1, thereis a process station B2 that is enclosed by a chassis 122 and coupled tothe carrier station B1. The process station B2 includes shelf units U1,U2, and U3 having heating and cooling units stacked one on another,liquid process units U4 and U5 (described below), and main transfermechanisms A2 and A3. The shelf units U1 through U3 are arranged in thisorder in a direction from the carrier station B1 to the process stationB2. The liquid process units U4 and U5 are arranged in this order in thesame direction, opposing the shelf units U1 through U3. The maintransfer mechanisms A2 and A3 transfer the wafer into/from each unit ofthe shelf units U1 through U3 and the liquid process units U4 and U5.Specifically, when seen from a Y direction in FIG. 3, the main transfermechanism A2 is arranged between the shelf units U1 and U2, and the maintransfer mechanism A3 is arranged between the shelf units U2 and U3.More specifically, the transfer mechanism A2 is positioned in a spacesubstantially defined by the shelf units U1, U2, the liquid process unitU4, and a partition wall 123. Similarly, transfer mechanism A3 ispositioned in a space substantially defined by the shelf units U2, U3,the liquid process unit U5, and a partition wall 123. Additionally,temperature/humidity control units that include a temperature controllerfor process agents used in the liquid process units U4, U5 and ducts orthe like for controlling temperature/humidity inside the chassis 122 areprovided in spaces indicated by “124” and “125” in FIG. 3.

The liquid process units U4 and U5 include coating units COT, developerunits DEV, anti-reflection coating units BARC and top coating units TC,which are stacked into plural (e.g., five) stages, as shown in FIG. 4.The shelf units U1 through U3 include various units stacked in plural(e.g., ten) stages, in which pre- and post-treatments are carried outbefore and after processes carried out in the liquid process units U4and U5. Specifically, the various units may be hydrophobizing processunits for hydrophobizing the wafer W, heating units for heating (baking)the wafer W, cooling units for cooling the wafer W, and the like.

The immersion exposure apparatus B4 where immersion exposure is carriedout is coupled to the process station B2 behind the shelf unit U3 via aninterface station B3. The interface station B3 includes a first transferchamber 126 and a second transfer chamber 127, which are arranged inthis order in a direction from the process station B2 to the exposureapparatus B4. The first transfer chamber 126 is provided with a firsttransfer arm A4, and the second transfer chamber 127 is provided with asecond transfer arm A5. The first and the second transfer arms A4, A5are elevatable, rotatable around a vertical axis, and slidable. Inaddition, the first transfer chamber 126 is provided with a shelf unitU6, a buffer cassette CO, and a cleaning apparatus 100 (describedbelow). The shelf unit U6 includes a high accuracy temperature controlunit having a heating unit and a cooling plate that are used to carryout post exposure bake, and a transfer unit that is used to transfer thewafer W between the first transfer arm A4 and the second transfer armA5. The high accuracy temperature control unit and the transfer unit arestacked one above another. The second transfer arm A5 transfers thewafer W to/from the cleaning apparatus 100.

The wafer W is transferred throughout the photoresist pattern formingsystem in the following manner. First, when the carrier C1 that housesthe wafers W is placed on the carrier stage 120, the opening/closingportion 121 is opened along with a lid of the carrier C1. Second, one ofthe wafers W is taken out from the carrier C1 by the transfer mechanismA1. Next, the wafer W is transferred to the main transfer mechanism A2through a transfer unit, which corresponds to one stage of the shelfunit U1, and then to the hydrophobizing unit, in which the wafer Wundergoes the hydrophobizing process. Subsequently, the wafer W istransferred to the anti-reflection coating unit BARC, in which ananti-reflection film is formed on the wafer W. Then, the wafer W isbaked in the heating unit.

Next, the wafer W is transferred to the coating unit COT, in which aphotoresist film is formed on the top surface of the wafer W. Then, thewafer W undergoes heat treatment in the heating unit, and furthertransferred to the interface station B3 by the main transfer mechanismA3 via a transfer unit of the shelf unit U3. The wafer W is transferredfrom the first transfer arm A4 to the second transfer arm A5 via thetransfer unit of the shelf unit U6, and then to the cleaning apparatus100 by the second transfer arm A5 in the interface station B3. In thecleaning apparatus 100, the top surface, the bevel portion, and the backsurface of the wafer W, which has not undergone the immersion exposure,are cleaned. When a protect film for the immersion exposure is coated onthe photoresist film, the protect film agent is coated in a unit (notshown) in the process station B2 after the wafer W is cooled in thecooling unit.

The wafer W cleaned in the cleaning apparatus 100 is transferred to theexposure apparatus B4 and undergoes the immersion exposure with, forexample, pure water layer formed on the top surface of the wafer W.Then, the wafer W, which has undergone the immersion exposure, is takenout from the exposure apparatus B4 and transferred to, for example, thecleaning apparatus 100 of the interface station B3, where remaining purewater on the top surface of the wafer W is eliminated. Next, the wafer Wis transferred to the heating unit, which corresponds to one stage ofthe shelf unit U6, and undergoes a post exposure baking (PEB) process.

Subsequently, the wafer W is taken out from the heating unit by thefirst transfer arm A4, transferred to the main transfer mechanism A3,and then transferred to the developer unit DEV by the main transfermechanism A3. After the wafer W undergoes a predetermined developingprocess in the developer unit DEV, the wafer W is baked in the heatingunit and then returned back to the carrier station B1 and thus thecarrier C1, to which the wafer W originally belongs, by the transfermechanism A1.

Next, the cleaning apparatus 100 incorporated into the above photoresistpattern forming system is described in detail in reference to FIGS. 5through 7, which are a perspective view, a plan view, and across-sectional view of the cleaning apparatus 100, respectively. Asshown in FIG. 5, the cleaning apparatus 100 includes a box-shaped undercup 43 having a top opening; two suction pads 2 as a first substrateholding portion that receives the wafer W from the second transfer armA5 of the coater/developer, which is a transfer arm outside of thecleaning apparatus 100, and holds the wafer W by suction; a spin chuck 3as a second substrate holding portion that receives the wafer W from thesuction pads 2 and substantially horizontally holds the wafer W bysuction; a brush 5 that cleans a first cleaning area in the back surfaceof the wafer W, the first cleaning area being substantially in thecenter portion of the back surface of the wafer W; a top surfacecleaning nozzle 6 that cleans the top surface of the wafer W; a bevelcleaning nozzle 7 that cleans the bevel portion of the wafer W; and aback periphery cleaning nozzle 8 that cleans a second cleaning area inthe back surface of the wafer W, the second cleaning area beingsubstantially outside of the first cleaning area.

First, the suction pads 2 as the first substrate holding portion aredescribed. As shown in FIG. 5, the cleaning apparatus 100 includes thetwo suction pads 2, each of which is configured of, for example, anelongated block. The two suction pads 2 are arranged in parallel witheach other, leaving a predetermined distance, in order to hold aperipheral area (a first area) in the back surface of the wafer W. Thetwo suction pads 2 are connected to corresponding suction tubes (notshown), and serve as vacuum chucks that hold the wafer W by suctionthrough suction holes 2 a shown in FIG. 6. As shown in FIG. 5, thesuction pads 2 are attached on a substantially center portion ofcorresponding pad supporting portions 21 having an elongated rod shape.The pad supporting portions 21 are attached on corresponding bridgingbeam portions 22. The pad supporting portions 21 and the bridging beamportions 22 constitute a double cross portion 20.

Both ends of the two bridging beam portions 22 are attached oncorresponding belts 23 wound around corresponding pairs of pulleys 24.The two pairs of the pulleys 24 are rotatably provided on correspondingside plates 26 that oppose corresponding side walls of the under cup 43.A driving mechanism 25 is coupled to one of the pair of the pulleys 24.With such a configuration, when the pulleys 24 are rotated by thedriving mechanism 25, the belts 23 can be moved around the pulleys 24along the corresponding side walls. As a result, the bridging beamportions 22 and thus the double cross portion 20 can move in an Xdirection shown in FIGS. 5 and 6.

Each of the side plates 26 is supported at its bottom surface by a pairof elevation mechanisms 27 composed of sliders 27 a and guide rails 27b, as shown in FIG. 5. The elevation mechanisms 27 are attached on achassis bottom surface (not shown) of the cleaning apparatus 100. Adriving mechanism (not shown) is coupled to one of the elevationmechanisms 27 in order to move upward/downward the slider 27 a along theguide rail 27 b, which can move the double cross portion 20 in a Zdirection shown in FIG. 5.

An upper cup 41 having substantially a ring shape is provided above thedouble cross portion 20 in order that mist or droplets of cleaning fluidare not scattered around. The upper cup 41 has an opening 41 a largerthan the diameter of the wafer W, through which the wafer W istransferred between the second transfer arm A5 and the suction pads 2.The wafer W can be held in a first cleaning position by the suction pads2. The upper cup 41 provided above the double cross portion 20 can movein the X and the Z directions along with the double cross portion 20, asshown in FIG. 5.

Next, the spin chuck 3 as the second substrate holding portion isdescribed. The spin chuck 3 has a disk shape and holds a back surfacecenter portion of the wafer W (a second area). The spin chuck 3 isarranged between the two suction pads 2 disposed in parallel with eachother. Therefore, the second area held by the spin chuck 3 is notoverlapped with the first area held by the suction pads 2. As shown inFIG. 7, the spin chuck 3 is coupled to a driving mechanism (spin chuckmotor) 33 via a shaft 3 b, so that the spin chuck 3 is rotatable arounda vertical axis and elevatable by the driving mechanism 33. Theelevation mechanism 27 that moves the double cross portion 20upward/downward and the driving mechanism 33 that moves and drives thespin chuck 3 constitute an elevation portion that moves the spin chuck 3(the second substrate holding portion) and the suction pads 2 (the firstsubstrate holding portion) upward/downward.

The spin chuck 3 is connected to a suction tube (not shown) in the samemanner as the suction pads 2 that is connected to the suction tube (notshown). With this, the spin chuck 3 serves as a vacuum chuck that holdsthe wafer W by suction through suction holes 3 a (FIG. 6). Moreover,supporting pins 32 are arranged in order to surround the spin chuck 3.The supporting pins 32 are connected to an elevation mechanism 32 a(FIG. 7), so that the supporting pins 32 can support the back surface ofthe wafer W and move the wafer W upward/downward. With the supportingpins 32 and a transfer mechanism (the second transfer arm A5) outside ofthe cleaning apparatus 100 working in cooperation with each other, thewafer W can be transferred from the transfer mechanism to the suctionpads 2, and from the suction pads to the spin chuck 3, and the oppositeway.

Referring to FIGS. 5 through 7, an air knife 31 having a cylindricalshape is located so as to enclose the spin chuck 3 and the supportingpins 32. As shown in FIG. 8, the air knife 31 has plural ejectionorifices 31 a at its top end. The ejection orifices 31 a are arrangedalong a circumferential direction. The air knife 31 ejects gas, forexample, pressurized air or the like supplied from a gas supplier (notshown) toward the back surface of the wafer W from the ejection orifices31 a so as to blow off the cleaning fluid on the back surface. Namely,the air knife 31 serves as a dryer to keep dry the top surface of thespin chuck 3 and the back surface to be contacted by the spin chuck 3(the second area). The air knife 31 is preferably composed of a dualcylinder having a hollow space between the two cylindrical walls, asshown in FIG. 8. With this configuration, the air knife 31 can eject thegas from the ejection orifices 31 a through the hollow space.

Next, the brush 5, which serves as a cleaning member that contacts andcleans the back surface of the wafer W, is described. The brush 5 iscomposed by bundling, for example, plural plastic strings into acylindrical column. The plastic strings may be made of, for example,polyvinyl chloride (PVC), urethane, nylon, or the like. The brush 5 isrotatably attached at the distal end of a supporting portion 51. Thesupporting portion 51 has a ladle-like shape so as not to obstruct themovement of the wafer W and the bridging beam portions 22. The base endof the supporting portion 51 is fixed on a belt 52 wound around a pairof spindles (or pulleys) 53 (FIG. 5) that are rotatably attached on oneof side walls extending along the Y direction. One of the spindles 53 isconnected to a driving mechanism 54 (FIGS. 5 and 6), which rotates thespindle 53 and moves the belt 52 in clockwise and counter clockwisedirections. In such a manner, the supporting portion 51 and thus thebrush 5 can move reciprocally along the Y direction shown in FIGS. 5 and6.

A rotating mechanism (not shown) is provided at the distal end of thesupporting portion 51 in order to rotate the brush 5. The brush 5 cancontact or be pressed onto the back surface of the wafer W and rotate inorder to remove particles on the back surface. Moreover, a cleaningfluid nozzle 5 a and a blowing nozzle 5 b are provided at the distal endof the supporting portion 51, as shown in FIG. 6. The cleaning fluidnozzle 5 a supplies the cleaning fluid, for example, DIW or purifiedwater in order to wash away the particles removed by the brush 5. Theblowing nozzle 5 b ejects gas, for example, nitrogen (N₂) so as tofacilitate drying the back surface of the wafer W after the back surfaceis cleaned.

In addition, the upper cup 41 is provided with a bevel cleaning nozzle 7for cleaning a bevel portion 70 (FIG. 9) of the wafer periphery. Thebevel cleaning nozzle 7 is configured to eject cleaning fluid such asDIW for cleaning the bevel portion 70 to wash away particles that are onthe bevel portion 70, when the wafer W is in the second cleaningposition. The bevel cleaning nozzle 7 includes an upper nozzle 71 forejecting the cleaning fluid to the bevel portion 70 in an orthogonaldirection from outside and above the wafer W, and a lower nozzle 72 forejecting the cleaning fluid to the bevel portion 70 in an orthogonaldirection from outside and below the wafer W, as shown in FIG. 9. Thetip portions of the upper nozzle 71 and the lower nozzle 72 arepositioned outside of a vertical transfer path of the wafer W so as notto obstruct the upward/downward movement of the wafer W in the upper cup41, as shown in FIG. 7.

The cleaning apparatus 100 also includes a top surface cleaning nozzle 6for cleaning the top surface of the wafer W in the second cleaningposition, as shown in FIG. 7. The top surface cleaning nozzle 6 includesa cleaning fluid nozzle 61 configured to eject cleaning fluid, forexample, DIW to the top surface of the wafer W in order to wash awayparticles that are on the top surface of the wafer W, and a gas nozzle62 configured to supply gas, for example, nitrogen (N₂) to the topsurface of the wafer W in order to dry the cleaning fluid from the topsurface of the wafer W. The cleaning fluid nozzle 61 and the gas nozzle62 are supported by a shared supporting portion 63, and movable in adirection along the diameter of the wafer W and elevatableupward/downward by a driving mechanism 64. When the wafer W istransferred to the cleaning apparatus 100, the cleaning fluid nozzle 61and the gas nozzle 62 are positioned above the wafer W being transferredso as not to obstruct the wafer W and the transfer mechanism.

The cleaning apparatus 100 further includes a back periphery cleaningnozzle 8 for cleaning the second cleaning area S2 in the back surface ofthe wafer W.

Next, the first cleaning area S1 and the second cleaning area S2 aredescribed in reference to FIG. 10. The second cleaning area S2 occupiesa ring-shaped area having a width of about 15 mm from the peripheraledge of the wafer W on the back surface of the wafer W. The firstcleaning area S1 is inside the second cleaning area S2. The secondcleaning area S2 includes an area affected by the hydrophobizing agent,so that the area presents hydrophobic property. The hydrophobizing agentis used and flows around the wafer edge to the back surface of the waferW in the hydrophobizing process, which is carried out before thephotoresist film is formed. The second cleaning area S2 is determined tobe larger than such a hydrophobic area by specifically estimating thehydrophobic area in advance.

The back periphery cleaning nozzle 8 is arranged so that cleaning fluidfor cleaning the back surface of the wafer W is ejected from the backperiphery cleaning nozzle 8 to the boundary between the first cleaningarea S1 and the second cleaning area S2 or around the boundary. Inaddition, the back periphery cleaning nozzle 8 is elevatable by anelevation mechanism 81. With this, the back periphery cleaning nozzle 8can be lowered in order not to interfere with the upper cup 41, theair-knife 31, and the like when the wafer W is horizontally shifted bythe suction pads 2. The back periphery cleaning nozzle 8 may beconfigured as, for example, a dual fluid nozzle. The cleaning fluid forcleaning the back surface of the wafer W may be a mixture of DIW andnitrogen. Namely, the dual fluid nozzle is configured to allow a liquidelement (DIW) and a gas element (nitrogen) to be mixed at and near thetip portion of the dual fluid nozzle, thereby ejecting the mixture tothe back surface of the wafer W.

Referring back to FIG. 7, the under-cup 43 has at its bottom portion adrain pipe 43 a for discharging from the under-cup 43 the cleaning fluidreceived by the under-cup 43 and two exhaust pipes 43 b for flowing outthe air inside the cleaning apparatus 100. The exhaust pipes 43 bprotrude upward from the bottom of the under-cup 43 in order to preventthe cleaning fluid remaining in the bottom from flowing into the exhaustpipes 43 b. A ring-shaped inner cup 42 is provided around the air-knife31 so as to be placed over the exhaust pipes 43 b in order to preventthe cleaning fluid from dribbling into the exhaust pipes 43 b.

A blowing nozzle 44 is provided above the upper-cup 41. The blowingnozzle 44 ejects gas, for example, pressurized air toward the topperipheral area or around the wafer W from above. The blowing nozzle 44is movable upward/downward by an elevating mechanism 45, which makes itpossible for the blowing nozzle 44 to move upward in order not to touchthe wafer W and the transfer arm A5 (FIG. 3) when the wafer W is beingtransferred in and out of the cleaning apparatus 100.

A lamp box 47 that houses a UV lamp 46 is attached on a side wall of theunder-cup 43, the side wall having no belts, as shown in FIG. 5. Thewafer W is transferred in and out of the cleaning apparatus 100, passingover the UV lamp 46. Therefore, the UV lamp 46 can emit ultravioletlight toward the back surface of the wafer W, while the wafer W is beingtransferred out of the cleaning apparatus 100, in order to shrinkparticles remaining, if any, on the back surface of the wafer W.

Next, a cleaning fluid supplier and a nitrogen gas supplier aredescribed in reference to FIG. 7. The cleaning fluid nozzle 61 and thegas nozzle 62 of the top surface cleaning nozzle 6 are connected to acleaning fluid (DIW) source 65 and a nitrogen gas source 66,respectively, via corresponding supply lines 61 a, 62 a havingcorresponding flow rate control units 61 b, 62 b. In addition, the bevelcleaning nozzles 71, 72 are connected to the cleaning fluid (DIW) source65 via a supply line 7 a having a flow rate control unit 7 b. The backperiphery cleaning nozzle 8 is connected to the cleaning fluid (DIW)source 65 and the nitrogen gas source 66 via corresponding supply lines81 a, 82 a having corresponding flow rate control units 81 b, 82 b. Inaddition, the blowing nozzle 44 is connected to the nitrogen gas source66 via a supply line 44 a having a flow rate control unit 44 b. The flowrate control units 61 b, 62 b, 7 b, 81 b, 82 b, and 44 b includecorresponding valves and flow controllers (not shown), and controlstarting/stopping supply of the cleaning fluid and the nitrogen gas andtheir flow rates under control of a controller 200 (described below).

Referring again to FIGS. 6 and 7, the cleaning apparatus 100 is providedwith a controller 200. The controller 200 controls operations of thecleaning apparatus 100. The controller 200 may be a computer to which aprogram storing unit 200 a is connected. The program storing unit 200 astores a computer program including steps (instructions) of causing eachcomponent or part of the cleaning apparatus 100 to perform predeterminedcleaning operations described below. The controller 200 retrieves thecomputer program from the program storing unit 200 a and controls thecomponents or parts in accordance with the program. Specifically, thecontroller 200 outputs instructions to various components or parts inorder to control the transfer mechanism A1, the main transfer mechanismsA2, A3, the transfer arms A4, A5, the suction pads 2, and the spin chuck3 to allow the wafer W to be transferred between the transfer mechanismsA1 through A3, the transfer arms A4, A5, the suction pads 2 and the spinchuck 3, and the brush 5, the top surface cleaning nozzle 6, the bevelcleaning nozzle 7, and the back periphery cleaning nozzle 8 and the liketo clean the wafer W.

The computer program is stored in a computer readable storage medium 200c, such as a hard disk, a CD-ROM/RAM, a magneto-optical disk, variousmemory cards, a USB memory, or the like, and loaded to the programstoring unit 200 a through an input/output (I/O) unit 200 b.

Next, cleaning operations performed by the cleaning apparatus 100 havingthe above configuration are described, in reference to FIGS. 11 through14B. In these drawings, the UV lamp 46 and the like are omitted in thesedrawings for simplicity of illustration.

As shown in FIG. 12A, the transfer arm A5 having a top view shape of “U”(or “C”) at the end (see FIG. 3) transfers the wafer W to be cleaned tothe cleaning apparatus 100 and stops at a standby position in order tokeep the wafer W above the upper opening 41 a of the upper cup 41. Next,the supporting pins 32 move upward from below the spin chuck 3 to aposition below the transfer arm A5. Then, the transfer arm A5 movesdownward from the standby position in order to allow the wafer W to reston the supporting pins 32, and subsequently retreats from the cleaningapparatus 100. At this time, the upper ends of the suction pads 2 arepositioned below the wafer W supported by the supporting pins 32 andabove the upper end of the brush 5. In addition, the upper surface ofthe spin chuck 3 is positioned below the upper end of the brush 5.Subsequently, when the supporting pins 32 move downward, the wafer W istransferred onto the suction pads 2 (FIG. 12B, step S111 in FIG. 11).

Then, the suction pads 2 hold the wafer W by suction so that the wafercannot be raised even when the brush 5 is pressed on the back surface ofthe wafer W. While holding the wafer W, the suction pads 2 are movedrightward to above the upper surfaces of the spin chuck 3, the brush 5,and the air-knife 31. After reaching a predetermined position, forexample, where the left edge of the air-knife 31 substantiallycorresponds to the left edge of the wafer W, the suction pads 2 movedownward and allow the back surface of the wafer W to touch the brush 5(FIG. 12C). In this situation, the altitude of the wafer W in the uppercup 41 corresponds to the first cleaning position. Specifically, thespin chuck 3 is positioned below the suction pads 2 and the top surfaceof the air-knife 31 is positioned slightly below the back surface of thewafer W.

Next, after the gas is blown out from the ejection orifices 31 a (FIG.8) of the air-knife 31, the cleaning fluid is ejected out from thecleaning fluid nozzle 5 a (FIG. 6) at the distal end of the supportportion 51 toward the back surface of the wafer W and the brush 5 isrotated, so that cleaning the center area in the back surface of thewafer W is started (Step S112). At this time, the gas blown out from theejection orifices 31 a of the air-knife 31 can prevent the cleaningfluid from splashing on the top surface of the spin chuck 3. While theback surface of the wafer W is being cleaned, the suction pads 2 and thebrush 5 cooperatively move in order to clean a wider area of the backsurface of the wafer W. Specifically, while the brush 5 is reciprocatingin the Y direction as shown in FIG. 14A, the suction pads 2 shift towardleft in the X direction by a distance smaller than the diameter of thebrush 5 when the brush 5 reverses the directions. Due to such movements,the brush 5 can trace a zigzag track on the back surface of the wafer Was shown by an arrow in FIG. 14A. As a result, a hatched line area T1 inFIG. 14A is uniformly cleaned. The area T1 includes the second area inthe back surface of the wafer W, i.e., that area which is to be laterheld by the spin chuck 3, and which, as shown in FIG. 14B, lies in thefirst cleaning area S1.

After the area T1 is cleaned, the suction pads 2 are moved back to theleft in order to bring the center of the wafer W in line with the centerof the spin chuck 3, and then the wafer W is transferred from thesuction pads 2 to the spin chuck 3, for example, in the following manner(FIG. 13A, step S113 in FIG. 11).

First, the brush 5 stops shifting and rotating while the gas is stillejected from the air-knife 31, and the cleaning fluid from the cleaningfluid nozzle 5 a at the distal end of the supporting portion 51 (FIG. 6)is stopped. Next, the wafer W is released from being fixed on thesuction pads 2, and the spin chuck 3 is raised to support the wafer Wfrom the back side of the wafer W. Then, the suction pads 2 are moveddownward and thus the wafer W is now placed on the spin chuck 3 and thespin chuck 3 then holds the wafer W by suction. The elevation of thewafer W placed on the spin chuck 3 corresponds to the elevation of thesecond cleaning position, which is above the first cleaning position inthis example.

Next, the top surface, the bevel portion 70, and the back surface of thewafer W are cleaned preferably concurrently, as shown in FIGS. 13A, 15A,and 15B, while the wafer is held at the second cleaning position by thespin chuck 3. In this example, the top surface cleaning fluid nozzle 6(61, 62) is brought downward so that the distal end of the cleaningnozzle 61 is positioned about 10 mm above the top center portion of thewafer W; the back periphery cleaning nozzle 8 is brought upward so thatthe distal end of the back periphery cleaning nozzle 8 is positionedabout 5 mm below the boundary between the first cleaning area S1 and thesecond cleaning area S2 or around the boundary; and the brush 5 ispressed onto the back surface of the wafer W. In this case, while theelevation of the wafer W is above the first cleaning position whencompared within the upper cup 41, the brush 5 can be pressed onto theback surface of the wafer W because the upper cup 41 (suction pad 2) isbrought down.

Next, while the wafer W is being rotated by the spin chuck 3, thecleaning fluid is supplied to the top surface, the bevel portion 70, andthe back periphery area from the top surface cleaning nozzle 6, thebevel cleaning nozzle 7, and the back periphery cleaning nozzle 8,respectively. At this time, the cleaning fluid is supplied to the backsurface of the wafer W form the cleaning fluid nozzle 5 a and the brush5 is also rotated. In this manner, the top surface, the bevel portion70, and the back periphery portion of the wafer W are cleaned (stepS114).

The top surface of the wafer W is cleaned, for example, in the followingmanner. First, the cleaning fluid F is supplied to the center portion ofthe wafer W, as shown in FIG. 15A. Then, the cleaning fluid nozzle 61 isshifted outward in the radius direction of the wafer W while supplyingthe cleaning fluid F. The gas nozzle 62 is also shifted outward, alongwith the cleaning fluid nozzle 61, and to a position above the centerportion of the wafer W (FIG. 15B). Here, the gas nozzle 62 blowsnitrogen gas (N₂) toward the center portion of the wafer W for about 2seconds. With this, after the cleaning fluid F is supplied to the centerportion of the wafer W from the cleaning fluid nozzle 61, the centerportion of the wafer W is dried by the N₂ gas from the gas nozzle 62. Inaddition, when the cleaning fluid nozzle 61 is slowly and continuouslyshifted toward the edge of the wafer W from the center portion of thewafer W while supplying the cleaning fluid F, the gas nozzle 62 is alsoslowly and continuously shifted along with the cleaning fluid nozzle 61while ejecting the N₂ gas. Thus, in this example, every part of the topsurface of the wafer W is cleaned by the cleaning fluid F supplied fromthe cleaning fluid nozzle 61 and then dried by the N₂ gas ejected fromthe gas nozzle 62. In addition, rotation of the wafer W causes thecleaning fluid F to flow outward by centrifugal force, thereby keepingdry dried part of the top surface of the wafer W.

While the gas nozzle 62 is shifted along with the cleaning fluid nozzle61 in the above explanation, the gas nozzle 62 need not necessarily beshifted. This is because the top surface of the wafer W may be dried aslong as the gas nozzle 62 can supply the N₂ gas toward the centerportion. Namely, only the cleaning fluid nozzle 61 may be slidable inthis case.

As shown in FIGS. 15A and 15B, the bevel portion 70 of the wafer W iscleaned with the cleaning fluid F ejected from the upper nozzle 71 andthe lower nozzle 72 while the wafer W is being rotated. Specifically,the cleaning fluid F is ejected with strong force to the bevel portion70 from the nozzles 71, 72, so that particles on the bevel portion 70can be removed by the colliding force of the cleaning fluid F. In thiscase, because the wafer W is being rotated, the cleaning fluid F canreach the entire bevel portion 70 of the wafer W, and be spun off fromthe bevel portion 70 by the centrifugal force caused by the rotation ofthe wafer W, which can flow the particles away from the bevel portion70.

The first cleaning area S1 (FIG. 10) of the back surface of the wafer Wis cleaned by cooperative movement of the spin chuck 3, which rotatesthe wafer W, and the brush 5, which shifts along the radius direction ofthe wafer W. For example, the brush 5 is first positioned so that thebrush 5 can clean an outermost portion of the first cleaning area S1 ofthe wafer W, and the spin chuck 3 slowly rotates the wafer W. Then, whenthe wafer W is rotated, for example, by 360 degrees, the brush 5 isshifted toward the center portion of the wafer W by a lengthcorresponding to a diameter or less of the brush 5. When such operationsare repeated, the brush 5 cleans the back surface of the wafer W, movingalong a concentric path on the back surface. Therefore, an area T2marked with diagonal lines rising from right to left (hatching) in FIG.14B can be uniformly cleaned.

On the other hand, the second cleaning area S2 is cleaned with the DIW(also shown by cleaning fluid “F” in FIGS. 15A and 15B) ejected from theback periphery cleaning nozzle 8. For example, the back peripherycleaning nozzle 8 is positioned at or around the boundary between thefirst cleaning area S1 and the second cleaning area S2, and ejects theDIW containing nitrogen bubbles. The DIW having reached the back surfaceof the wafer W flows on the back surface of the wafer W toward the edgeof the wafer W by centrifugal force. Therefore, the second cleaning areaS2 is wet with the DIW. In addition, when the DIW is spun off from theedge of the wafer W by the centrifugal force, the particles are alsowashed away from the wafer W by the DIW. Moreover, when the backperiphery cleaning nozzle 8 is configured into a dual fluid nozzle, theimpact of the DIW onto the back surface of the wafer W is enhanced.Therefore, the particles can be struck up by the colliding force andeasily washed away, leading to an efficient cleaning effect.

When cleaning is being carried out at step S114 as explained in theabove exemplary manner, the back surface of the wafer W is covered orsubstantially covered by a cleaning fluid film F, and the particlesremoved by the brush 5 are washed away along with the cleaning fluidthat falls down from the back surface of the wafer W toward the undercup 43. In addition, because the gas is ejected toward the back surfaceof the wafer W from the ejection orifices 31 a of the air-knife 31during the cleaning, the cleaning fluid (DIW) is blown outward, so thatpart of the back surface opposing the air-knife 31 can be kept dry.Namely, the air-knife 31 prevents the cleaning fluid from reaching thespin chuck 3, thereby keeping the spin chuck 3 dry. While water marksmay be formed on the back surface of the wafer W when, for example, thetop surface of the spin chuck 3 is wet, such water marks are not formedin the above configuration because the top surface of the spin chuck 3is kept dry.

As shown in FIG. 14B, a combined area of the area T1 and the area T2 ofthe back surface of the wafer W covers completely the first cleaningarea S1 of the back surface of the wafer W without leaving uncleanedareas, which is realized by adjusting in advance, for example, the sizeand operations of each component or part of the cleaning apparatus 100.Especially, when part of the brush 5 may enter an area, which is nothydrophobized in the second cleaning area S2, the entire first cleaningarea S1 is assuredly cleaned.

Because the DIW is used as the cleaning fluid F for cleaning the topsurface, the bevel portion 70, and the back surface of the wafer W,these areas can be cleaned concurrently without any disadvantage thatmay be caused when different cleaning fluids are used. In addition, whenthe top surface, the bevel portion 70, and the back surface of the waferW are concurrently cleaned, even if mist (or droplets) of the cleaningfluid, which may include particles, is caused above the top surface ofthe wafer W and scattered to, for example, the bevel portion 70, suchmist (droplets) can be washed away from the bevel portion 70, becausethe bevel portion 70 is being cleaned at the same time. In other words,particles can be removed from the wafer W by concurrently cleaning thetop surface, the bevel portion 70, and the back surface of the wafer W,and thus the cleaning effect is improved.

After the top surface, the bevel portion 70, and the back surface of thewafer W are cleaned in the above manner, the top cleaning nozzle 6 ismoved upward, and the back periphery cleaning nozzle 8 is moveddownward. In addition, the brush 5 stops rotating and shifting; thecleaning fluid nozzle 5 a stops supplying the cleaning fluid; and thespin chuck 3 stops rotating. Then, the spin chuck 3 starts spinning thewafer W in order to spin off the cleaning fluid remaining mainly on theback surface of the wafer W, and as a result, the wafer W is dried (stepS115 in FIG. 11). Since the cleaning fluid remaining on the back surfaceis suddenly spun off, the wafer marks are not formed. At this time, theblowing nozzle 44, which has been retreated upward, is moved downward asshown in FIG. 13B, and the supporting portion 51 is moved so that theblowing nozzle 5 b next to the brush 5 is positioned below the bevelportion 70 of the wafer W. With this, the gas can be blown to the bevelportion 70 from above and below, thereby drying the bevel portion 70 ofthe wafer W. Although the second area of the back surface of the waferW, which is held at the top surface of the spin chuck 3, is not subjectto any drying procedures, no water marks are formed in the second area,because the second area can be kept dry in the first place by theair-knife 31, for example.

After cleaning and drying the back surface of the wafer W are completedas explained above, the wafer W is transferred to the transfer arm A5(FIG. 3) in an opposite way of transferring the wafer W to the cleaningapparatus 100. When the wafer W is being transferred out, the UV lamp 46is turned on and ultraviolet light is irradiated from the UV lamp 46(FIGS. 5 and 6) toward the back surface of the wafer W that is beingsupported by the transfer arm A5 (FIG. 3) whose wafer-supporting end isU-shaped. Even if particles remain on the back surface of the wafer W,since the UV light can decompose organic substances, the particles whichmay originate from the photoresist can be shrunk and removed from theback surface, thereby facilitating elimination of the defocusingproblem.

While the wafer W is transferred from the cleaning apparatus 100, thesuction pads 2 and the spin chuck 3 are moved back to standby positions,for example, the positions shown in FIG. 12A and wait for the next waferto be transferred in. After the next wafer is transferred in, theprocedures explained in reference to FIGS. 12A through 15B are repeated,and in such a manner plural wafers are processed in series.

<Second Embodiment>

Referring to FIGS. 16 through 18, a cleaning apparatus according to asecond embodiment of the present invention is described. In thesedrawings, the same or corresponding reference marks used in FIGS. 1through 8 are given to the same or corresponding members or components.

A cleaning apparatus 110 according to the second embodiment is differentfrom the cleaning apparatus 100 according to the first embodiment inthat the spin chuck 3 as the second substrate holding portion can bemoved further downward below the second area in the back surface of thewafer W in order to allow the brush 5 to move above the spin chuck 3. Inaddition, the double cross portion 20 is fixed in the X direction andelevatable in the Z direction in the cleaning apparatus 110 according tothe second embodiment, in contrast to the cleaning apparatus 100. Theelevating mechanism 27 (FIG. 5) that moves the double cross portion 20upward/downward, and the spin chuck motor 33 (FIG. 7) that moves thespin chuck 3 upward/downward serve as an elevating portion that canvertically move the spin chuck 3, which serves as the second waferholding portion, in relation to the suction pads 2, which serve as thefirst wafer holding portion. The brush 5 is attached at the distal endof the supporting portion 51, and the base end of the supporting portion51 is fixed on the under cup 43. The supporting portion 51 is configuredto be pivotable around a pivot 51 a provided at the base end andretractable in order to elongate and contract, as shown in FIG. 16. Withsuch a configuration, the brush 5 can clean the back surface of thewafer W from center (the second area) to edge without shifting the waferW.

Referring to FIGS. 16 through 18, the cleaning apparatus 110 accordingto the second embodiment of the present invention includes a covermember 91 and a retractable supporting portion 92 for supporting thecover member 91. The cover member 91 is made of a water repellentmaterial such as a fluorine resin or the like and has a diameter largerthan or equal to the diameter of the top surface of the spin chuck 3.The base end of the supporting portion 92 is fixed on the top end of theside wall opposing the side wall where the base end of the supportingportion 51 is fixed. The cover member 91 attached at the distal end ofthe supporting portion 92 is in a standby position when the supportingportion 92 is retracted (FIG. 17A), and in a position over the spinchuck 3 when the supporting portion 92 is extended (FIG. 17B). With sucha configuration, the cover member 91 can prevent the cleaning fluid fromdribbling down on the top surface of the spin chuck 3 when the backsurface of the wafer W is being cleaned. In addition, the cover member91 may have plural ejection orifices at the circumferential portion inother embodiments, so that gas such as N₂ gas or the like can be blownout downward from the ejection orifices. With these orifices, the topsurface of the spin chuck 3 is preferably prevented from being wet withmist or droplets caused from the cleaning fluid when the back surface ofthe wafer W is being cleaned. Since the cleaning apparatus 100 accordingto this embodiment does not include the air-knife 31, the ejectionorifices of the cover member 91 are advantageous.

Moreover, the supporting portion 92 is provided with a back surfacecleaning nozzle 93 configured to supply the cleaning fluid to the secondcleaning area S2 in the back surface of the wafer W in order to cleanthe second cleaning area S2 and a drying nozzle 94 configured to blowgas toward the second area S2 of the back surface of the wafer W. Thedrying nozzle 94 serves as a drying portion that dries the second areaof the back surface of the wafer W.

Next, operations of the cleaning apparatus 110 according to the secondembodiment of the present invention are described. Referring to FIG.17A, when the wafer W is transferred, the spin chuck 3 is positioned atthe lower portion of the under cup 43 and the cover member 91 ispositioned at the standby position (an upper lateral position withrespect to the spin chuck 3). When the second transfer arm A5 brings thewafer W above the upper cup 41, the supporting pins 32 receive the waferW from the second transfer arm A5 and place the received wafer W ontothe suction pads 2. The suction pads 2, in turn, draw the wafer W usinga suction tube (not shown in FIG. 17A) in order to hold the wafer W onthe top of the suction pads 2.

Next, as shown in FIG. 17B, the supporting pins 32 are lowered so thatthe top ends of the supporting pins 32 are positioned below the topsurface of the spin chuck 3; the supporting portion 92 is elongated inorder to bring the cover member 91 over the spin chuck 3; and thesupporting portion 51 is extended in order to bring the brush 5 belowthe center area of the back surface of the wafer W. Then, the suctionpads 2 are lowered so that the brush 5 touches the back surface of thewafer W, and the center area, which includes the second area, is cleanedby rotating the brush 5 along with the cleaning fluid supplied towardthe back surface from the cleaning fluid nozzle 5 a (FIG. 6). As statedabove, because the cover member 91 covers the spin chuck 3, acting likean umbrella, and the gas may be blown out downward from the cover member91 in order to blow the mist or droplets away, the top surface of thespin chuck 3 is kept dry. After the center area of the back surface ofthe wafer W are cleaned, the supporting portion 51 is retracted to movethe brush 5 toward the edge portion of the wafer W. Then, the dryingnozzle 94 starts blowing the gas toward the second area, which is thusdried.

After the second area of the back surface of the wafer W is dried, thecover member 91 is moved back to the standby position, as shown in FIG.18. Next, the spin chuck 3 is raised so that the top surface of the spinchuck 3 touches the cleaned and dried second area, and the wafer W istransferred from the suction pads 2 to the spin chuck 3, which thenholds the wafer W by suction. Then, the wafer W is slowly rotated by thespin chuck 3. Next, the cleaning fluid is supplied to the back surfaceof the wafer W from the back periphery cleaning nozzle 8 (FIG. 15A), andthe brush 5 is rotated and shifted by the supporting portion 51 that canbe extended/contracted and is pivotable around the pivot 51 a (FIG. 16)of the supporting portion 51. This is how the uncleaned area of thesecond cleaning area S2 and the first cleaning area S1 are cleaned. Atthis time, the cleaning fluid nozzle 61 and the bevel portion cleaningnozzle 71, 72 may eject cleaning fluid, so that the top surface and thebevel portion 70 are cleaned in such a manner described in the firstembodiment.

When the back surface of the wafer W is cleaned by rotating the wafer W,the supporting pins 32 which stay in the lower portion of the under cup43 are preferably prevented from being wetted with the cleaning fluid,for example, by housing the pins 32 in a capsule or the like (notshown).

After the above cleaning is completed, the wafer W is spun at a highspeed by the spin chuck 3 so that the cleaning fluid on the wafer W isspun off and thus the wafer W becomes dry. Then, the wafer W istransferred from the spin chuck 3 to the supporting pins 32 in anopposite way of transferring the wafer W to the cleaning apparatus 110and thus to the second transfer arm A5 (FIG. 3), and transferred outfrom the cleaning apparatus 110. It is apparent that the UV lamp 46(FIGS. 5 and 6) may be used (turned on) also in this embodiment when thewafer W is being transferred out from the cleaning apparatus 110.

According to the cleaning apparatuses 100, 110 of the embodiments of thepresent invention, because the back surface of the wafer W is cleanedwhile the wafer W is supported from the back surface and kept face up,there is no need for a reverser that reverses the wafer for the purposeof cleaning the back surface of the wafer W, which eliminates the spacerequired to implement the reverser and the space required to reverse thewafer W in the cleaning apparatuses 100, 110. As a result, thephotoresist coater/developer or the photolithography system can be madecompact when the cleaning apparatuses 100, 110 according to theembodiments of the present invention are integrated into the photoresistcoater/developer or the system, compared with the conventionalphotoresist coater/developer or photolithography system.

In addition, because the wafer W is once held by the suction pads 2 andthen by the spin chuck 3, or vice versa, when the back surface of thewafer W is cleaned in the cleaning apparatuses 100, 110, a regioncovered by the suction pads 2 can be cleaned when the wafer W is held bythe spin chuck 3, and another region covered by the spin chuck 3 can becleaned when the wafer W is held by the suction pads 2. In such amanner, the back surface of the wafer W can be entirely cleaned.

Moreover, because the wafer W is held face up when the back surface ofthe wafer W is cleaned in the cleaning apparatuses 100, 110, thecleaning fluid can be concurrently supplied to the top surface and thebevel portion 70 of the wafer W. In other words, the top surface, thebevel portion 70, and the back surface of the wafer W can be cleaned inone cleaning apparatus. If three cleaning apparatuses are used forcleaning the top surface, the bevel portion 70, and the back surface ofthe wafer W, respectively, the wafer W has to be transferred to thosecleaning apparatuses one right after another, leading to reduction ofproduction throughput.

Furthermore, because cleaning the top surface, the bevel portion 70, andthe back surface (the first and the second cleaning areas S1, S2) of thewafer W can be overlapped time wise, a total cleaning time can beshortened.

In addition, the cleaning apparatuses 100, 110 may only occupy a spacesufficient for one cleaning apparatus in a coater/developer whenincorporated in the coater/developer, which can address the needs ofavoiding an increased footprint as well as cleaning the wafer W withinthe coater/developer before the immersion exposure.

Moreover, when the first cleaning area S1 and the second cleaning areaS2 (FIG. 10) in the back surface of the wafer W are cleaned, appropriateways of cleaning can be chosen for each area, depending on their surfaceproperties, thereby reducing particle generation during cleaning.Namely, while the first cleaning area S1 is cleaned by the brush 5 (FIG.5) with the DIW supplied from the cleaning fluid nozzle 5 a (FIG. 6),the second cleaning area S2 is cleaned by ejecting the DIW with the N₂bubbles from the back periphery cleaning nozzle 8. Because the secondcleaning area S2 may be hydrophobized by hydrophobizing agent flowingaround the edge to the back surface of the wafer W, the second cleaningarea S2 is likely to stay dry off of the cleaning fluid (DIW). In thiscase, if the second cleaning area S2 is cleaned by the brush 5, thebrush 5 may be worn away on the dry surface of the second cleaning areaS2, generating particles. However, the use of the back peripherycleaning nozzle 8 can avoid such particle generation. In addition, whenthe back periphery cleaning nozzle 8 is configured into the dual fluidnozzle, colliding force of the DIW and the N₂ bubbles can be increased,thereby assuredly removing the particles.

Although the present invention has been described in conjunction withthe foregoing specific embodiments, many alterations and modificationswill be apparent to those skilled in the art. For example, while the topsurface, the bevel portion 70, and the back surface of the wafer W areconcurrently cleaned in the above embodiments, this need not be thecase. After one of the top surface, the bevel portion 70, and the backsurface of the wafer W is cleaned, the others may be cleaned.Alternatively, after the top and the back surfaces are concurrentlycleaned, the bevel portion 70 may be cleaned. In addition, after one ofthe first and the second cleaning areas S1, S2 are cleaned, the othermay be cleaned. It should be noted here that “concurrently cleaned”includes that two or more the top surface, the bevel portion 70, and theback surface of the wafer W are cleaned during an overlapped timeperiod. In addition, cleaning the top surface, the bevel portion 70, andthe back surface of the wafer W can be started or ended with time lag,as long as the cleaning time period is overlapped.

While the second cleaning area S2 in the back surface of the wafer W isnot cleaned by the brush 5 in the above embodiments, the second cleaningarea S2 may be cleaned with the brush 5 in some instances. For example,when a sufficient amount of the cleaning fluid (DIW) can be suppliedfrom the back periphery cleaning nozzle 8, the cleaning fluid may remainon the second cleaning area S2 even if the second cleaning area S2 ishydrophobized, which prevents the brush 5 from being worn out. Inaddition, when the hydrophobizing process is not carried out on thewafer W, the second cleaning area S2 and thus the entire back surface ofthe wafer W can be cleaned by the brush 5.

Moreover, the top surface cleaning nozzle 6, the bevel cleaning nozzle7, and the back periphery cleaning nozzle 8 are not limited to thoseexplained above in terms of their configuration, as long as the topsurface cleaning nozzle 6, the bevel cleaning nozzle 7, and the backperiphery cleaning nozzle 8 can supply the cleaning fluid (DIW) to thetop surface, the bevel portion 70, and the back surface of the wafer Wheld by the spin chuck 3, respectively. For example, in addition to thedual fluid nozzle described above, a jet nozzle, a megasonic nozzle, andthe like may be used to configure the nozzles 6, 7, 8.

Moreover, different cleaning fluids may be supplied from the top surfacecleaning nozzle 6, the bevel cleaning nozzle 7, and the back peripherycleaning nozzle 8. Furthermore, these nozzles 6, 7, 8 may supply two ormore cleaning fluids. In this case, the nozzles 6, 7, 8 can supply onecleaning fluid for one period of time and another cleaning fluid foranother period of time. Additionally, after one of the top surface, thebevel portion 70, and the back surface of the wafer W is cleaned withone cleaning fluid, another may be cleaned with another cleaning fluid.

The top view shape of the suction pads 2 is not limited to the elongatedrectangle shown in FIG. 6. For example, the suction pads 2 may have anarc-like top view shape in such a manner that the top view shape iscurved along a circle concentric with the wafer edge of the wafer heldby the suction pads 2. The suction pads 2 having such a top view shapeallow a larger area of the back surface between the suction pads 2.Therefore, such suction pads 2 are advantageous in that the larger areacan be cleaned when the wafer W is held by the suction pads 2, and thebrush 5 is less likely to be hindered by the suction pads 2.

While the cleaning apparatuses 100, 110 employ the brush 5, which mayprovide a high cleaning performance, as the cleaning member, thecleaning member is not limited to the brush 5 herein. For example, othertypes of cleaning members that can eject the cleaning fluid or the liketoward the back surface of the wafer in order to remove particles on theback surface can be employed instead of the brush 5. Such cleaningmembers may be a dual-fluid nozzle, a jet nozzle, a megasonic nozzle, orthe like. In addition, although the brush 5 is of a rotating type in theabove embodiments, a brush of a vibrating type can be used. Furthermore,the cleaning fluid is not limited to the DIW or the purified water butother fluids can be used.

Additionally, while the cleaning apparatuses 100, 110 include 2 types ofsubstrate supporting portions (the suction pads 2 and the spin chuck 3),the cleaning apparatuses 100, 110 may have three or more substratesupporting portions. For example, when the cleaning apparatuses 100, 110have three substrate supporting portions L, M, and N (not shown), thewafer can be transferred twice, that is, from the substrate supportingportion L to the substrate supporting portion M, and from the substratesupporting portion M to the substrate supporting portion N. In thiscase, the substrate supporting portions M, N, for example, areconsidered as the first and the second substrate supporting portions,respectively.

Moreover, the photoresist coater/developer to which the cleaningapparatuses 100, 110 according to the embodiments of the presentinvention are incorporated is not limited to the one described above.Furthermore, the cleaning apparatuses 100, 110 according to theembodiments of the present invention may be provided in the processstation B2 rather than the interface station B3.

The present application is based on Japanese Patent Application No.2008-30857 filed with the Japanese Patent Office on Feb. 12, 2008, theentire contents of which are hereby incorporated herein by reference.

What is claimed is:
 1. A cleaning apparatus that cleans a substrate onwhich a photoresist film is formed, the photoresist film being exposedto exposure light with a liquid layer being formed on a top surface ofthe photoresist film, the cleaning apparatus comprising: a firstsubstrate holding portion configured to hold the substrate at a firstarea in a back surface of the substrate so that the top surface is keptface up; a second substrate holding portion configured to hold thesubstrate at a second area in the back surface of the substrate, thesecond area not overlapping with the first area, and the secondsubstrate holding portion being configured to rotate the substrate; agas ejection portion having a cylindrical shape that encloses the secondsubstrate holding portion, the gas ejection portion including aplurality of ejection orifices that are arranged at an upper end of thegas ejection portion and opened toward the back surface of thesubstrate, the gas ejection portion ejecting gas through the pluralityof the ejection orifices toward a rotational axis of the secondsubstrate holding portion; a top surface cleaning nozzle configured tosupply a top surface cleaning fluid to a top surface of the substrate; abevel cleaning nozzle configured to supply a bevel cleaning fluid tobevel portions of the substrate, the bevel cleaning nozzle including anupper nozzle and a lower nozzle, the upper nozzle ejecting the bevelcleaning fluid to the bevel portion that is a slanted portion facingobliquely upward from outside and above the top surface of thesubstrate, the lower nozzle ejecting the bevel cleaning fluid to thebevel portion that is a slanted portion facing obliquely downward fromoutside and below the back surface of the substrate, the upper and lowernozzles being positioned such that tip portions of the upper and lowernozzles are disposed outside of a vertical transfer path of thesubstrate, so as to not obstruct vertical movement of the substratewhile the substrate is being rotated, and the bevel cleaning nozzlesbeing configured so as to eject the bevel cleaning fluid to therespective bevel portions orthogonally; a cleaning fluid supplyingportion disposed outside the gas ejection portion and configured tosupply a back surface cleaning fluid to the back surface of thesubstrate held by the first substrate holding portion or the secondsubstrate holding portion; a cleaning member disposed outside the gasejection portion and configured to clean the back surface of thesubstrate held by the first substrate holding portion or the secondsubstrate holding portion, a moving mechanism configured to laterallymove the first substrate holding portion relative to the secondsubstrate holding portion; and an elevation mechanism configured tovertically move the first substrate holding portion and the secondsubstrate holding portion relative to each other, wherein the gasejection portion dries an inside area including the second area in theback surface of the substrate by blowing off the cleaning fluid in theinside area including the second area of the back surface of thesubstrate by the ejected gas.
 2. The cleaning apparatus of claim 1,further comprising a controller configured to output an instruction inaccordance with which a first one part of the back surface of thesubstrate, the first one part including the second area, is cleaned bythe cleaning member while the substrate is held by the first substrateholding portion, the substrate is transferred from the first substrateholding portion to the second substrate holding portion, and anotherpart of the back surface of the substrate, the another part notincluding the second area, is cleaned by the cleaning member while thesubstrate is rotated by the second substrate holding portion.
 3. Thecleaning apparatus of claim 2, wherein the controller is furtherconfigured to output another instruction in accordance with which, in atime period during which a second one part of the back surface, thesecond one part not including the second area, is cleaned by thecleaning member, the top surface cleaning fluid is supplied to the topsurface of the substrate from the top surface cleaning nozzle, and thebevel cleaning fluid is supplied to the bevel portion of the substratefrom the bevel cleaning nozzle.
 4. The cleaning apparatus of claim 1,further comprising a back periphery cleaning nozzle configured to supplya back periphery cleaning fluid to a back peripheral area in thesubstrate held and rotated around a substantial center of the substrateby the second substrate holding portion.
 5. The cleaning apparatus ofclaim 4, further comprising a controller configured to output aninstruction in accordance with which, in a time period during which onepart of the back surface, the one part not including the second area, iscleaned by the cleaning member, the top surface cleaning fluid issupplied to the top surface of the substrate from the top surfacecleaning nozzle, the bevel cleaning fluid is supplied to the bevelportion of the substrate from the bevel cleaning nozzle, and the backperiphery cleaning fluid is supplied to the back surface of thesubstrate from the back periphery cleaning nozzle.
 6. A coater anddeveloper comprising: a coating unit configured to coat a photoresistfilm on a top surface of a substrate; a developing unit configured tosupply a developing solution to the photoresist film coated on the topsurface of the substrate, the photoresist film being exposed to exposurelight with a liquid layer being formed on the photoresist film, therebydeveloping the photoresist film; and a cleaning apparatus according toclaim
 1. 7. The cleaning apparatus of claim 1, wherein the firstsubstrate holding portion includes first and second suction pads.
 8. Thecleaning apparatus of claim 1, further comprising an upper cup toprevent scattering of cleaning fluid, the upper cup being disposed so asto move laterally and vertically with movement of the first substrateholding mechanism.
 9. The cleaning apparatus of claim 1, wherein thefirst substrate holding portion includes first and second suction pads;first and second pad supporting portions, on which the first and secondsuction pads are disposed, respectively; first and second bridging beamportions, on which opposite ends of each of the first and second padsupporting portions are disposed, respectively; and first and secondconveying belts disposed on opposite sides of an under cup of thecleaning apparatus, wherein opposite ends of each of the first andsecond bridging beam portions are attached to the first and secondconveying belts, respectively.
 10. The cleaning apparatus of claim 7,wherein the first and second suction pads are elongated, and wherein thefirst and second suction pads are disposed on opposing sides of thesecond substrate holding portion such that longitudinal directions ofthe first and second suction pads are parallel to each other.